Plot
The family, after visiting a pancake house, visits Mrs. Wickerbottom's Pre-Nursery School, where Apu and Manjula are sending two of their octuplets. Homer and Marge have a talk with Dr. Hibbert about getting in, and decide to have Maggie go in. However, Maggie fails the initial screening because she cannot talk, until Lisa discovers some traits of intelligence. Homer and Marge make another screening. The results show that not only is Maggie brilliant, but her IQ of 167 is higher than Lisa's IQ of 159. Lisa is no longer considered "the smart one" of the Simpson family. Her attempts to find a new identity, including a goth named Ravencrow Neversmiles, a cheerleader, a rapper, a soccer player, a cowgirl, and even a stand-up comedian, do not work out well.

At home, Lisa teaches Maggie false information. Homer (with the Phonic Frog) and Marge denounce her for trying to sabotage her sister's education. She leaves the house and hides in the Natural History Museum, where there is no chance of Homer and Marge finding her, until Chief Wiggum, Lou and Eddie find her in there. The family goes in the human body, but Maggie "accidentally" presses the swallow button, swallowing both her parents (Homer and Marge) and her remaining sibling (Bart). Maggie presses many buttons until she finally presses the evacuate button. Ironically, after Maggie saves Homer, Marge, and Bart, she no longer has a secret to her intelligence Ã¢â‚¬â€ it turns out Lisa was subconsciously showing her answers. Maggie, however, plays Lisa's saxophone in the end, showing another sign of intelligence; a worried Lisa reclaims her saxophone and tells her that it's not for babies.